1. Field of the Invention
The present application relates to methods and apparatuses for welding together a plurality of pieces of metal at a joint between the pieces of metal.
2. Description of Related Art
Recently commercialized hybrid laser arc welding is a method of welding two pieces of metal together which typically combines laser beam welding with gas metal arc welding, for example, on the same side of a joint between the pieces of metal to simultaneously direct both a laser beam and an electric arc at one welding zone to produce a common molten metal pool which solidifies to form a weld. As illustrated in FIG. 1a, a prior art apparatus may accomplish this by directing the laser beam output 10′ from a laser 10 (which may comprise a laser resonator and associated optics) and the electric arc output 12′ from a gas metal arc welder 12 at the first side 14a of a joint 14 in order to weld a first piece of metal 16a to a second piece of metal 16b to form the joint. Hybrid laser arc welding may increase both the welding speed and the weld penetration depth as compared to conventional arc welding techniques. However, as illustrated in FIG. 1b, the resulting weld 18 may be enhanced much more so on the first side 14a of the joint 14, which is the side that the laser beam output 10′ and the electric arc output 12′ act on, as opposed to an opposite second side 14b of the joint. In particular, the weld 18 may not extend completely through the joint 14 from the first side 14a to the second side 14b. Further, when the weld 18 does reach the second side 14b of the joint 14, a second portion of the weld 18b may be significantly less thick than a first portion 18a of the weld on the first side 14a of the joint.
One attempt to make a more symmetric weld on both sides of the joint has been to operate the hybrid laser welder described above on the first side 14a of the joint 14, followed by either moving the hybrid laser welder to the second side 14b of the joint or turning over the pieces of metals 16a, b to direct the laser beam output 10′ and the electric arc output 12′ against the second side of the joint. As illustrated in FIG. 1c, operating the hybrid laser welder first on the first side 14a of the joint 14 and then the second side 14b of the joint may produce a weld 18′ which has been enhanced on both sides of the joint. This weld 18′ may be more desirable due to it extending more fully and completely from the first side 14a to the second side 14b of the joint 14, which may provide both strength and cosmetic benefits. However, the additional time required to move the hybrid laser welder or rotate the pieces of metal and make two sequential passes with the welding equipment is undesirable.
An alternate method which has been developed is to provide a hybrid laser welder on each side of the joint. This embodiment avoids the disadvantage of requiring movement of the metal pieces or the hybrid laser equipment from one side to the other. In addition, welding-induced distortion or deformation in this case may be less than the 2-pass sequential welding process mentioned above. However, this solution uses a second laser. Since the lasers used to complete the laser hybrid welding operation may be very expensive, it may be undesirable to operate two separate hybrid laser welders on the joint.
Accordingly, a need exists in the art for an improved welding apparatus and corresponding method of welding.